[Bug c++/94112] New: Please add a warning for potentially throwing code in noexcept function

[Bug c++/94112] New: Please add a warning for potentially throwing code in noexcept function

[rafael at espindo dot la]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94112

            Bug ID: 94112
           Summary: Please add a warning for potentially throwing code in
                    noexcept function
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rafael at espindo dot la
  Target Milestone: ---

GCC produces a warning for

void foo() noexcept {
    throw 42;
}

But not for

static void bar() {
    throw 42;
}
void foo() noexcept {
    bar();
}

Such a warning would be quite handy for checking the usage of noexcept in a
codebase.

[Bug c++/94112] Please add a warning for potentially throwing code in noexcept function

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94112

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-03-10
                 CC|                            |msebor at gcc dot gnu.org
             Blocks|                            |87403

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Confirmed with the output below.  -Wterminate is fully implemented in the C++
front-end so it doesn't know about what might happen in called functions. 
Implementing the detection across inlined functions requires moving the warning
to the middle-end and deciding how to deal with situations where the called
function throws only under some non-constant conditions (e.g., issue
-Wterminate regardless, or a -Wmaybe-terminate kind of a warning, or none).

$ gcc -O2 -Wall -Wextra -S -Wall a.C
void foo () noexcept
{
    throw 42;
}

static void bar ()
{
    throw 42;
}

void foobar () noexcept
{ 
    bar ();
}

a.C: In function ‘void foo()’:
a.C:3:5: warning: ‘throw’ will always call ‘terminate’ [-Wterminate]
    3 |     throw 42;
      |     ^~~~~~~~


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87403
[Bug 87403] [Meta-bug] Issues that suggest a new warning

[Bug c++/94112] Please add a warning for potentially throwing code in noexcept function

[rafael at espindo dot la]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94112

--- Comment #2 from Rafael Avila de Espindola <rafael at espindo dot la> ---
(In reply to Martin Sebor from comment #1)
> Confirmed with the output below.  -Wterminate is fully implemented in the
> C++ front-end so it doesn't know about what might happen in called
> functions.  Implementing the detection across inlined functions requires
> moving the warning to the middle-end and deciding how to deal with
> situations where the called function throws only under some non-constant
> conditions (e.g., issue -Wterminate regardless, or a -Wmaybe-terminate kind
> of a warning, or none).


I would be happy even with a "noexcept function calls a non-noexcept one"
warning.

[Bug c++/94112] Please add a warning for potentially throwing code in noexcept function

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94112

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
That would likely be far too noisy for use 99% of the time.

[Bug c++/94112] Please add a warning for potentially throwing code in noexcept function

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94112

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |egallager at gcc dot gnu.org
         Resolution|---                         |DUPLICATE
             Status|NEW                         |RESOLVED

--- Comment #4 from Eric Gallager <egallager at gcc dot gnu.org> ---
dup of bug 61372

*** This bug has been marked as a duplicate of bug 61372 ***